Television broadcast studios currently employ an FCC (Federal Communications Commission)-established standard, NTSC-signalling format for the broadcast of television programming to customer sites. Because the transmission facility (typically a microwave transmission tower) from which the television signals are broadcast (via VHF and/or UHF channels) over a prescribed customer service area is customarily located off-campus from the television studio, a dedicated (microwave) radio link is provided between the television studio and the tower, so that the NTSC-formatted television programming may be forwarded from the studio to the tower for broadcast. In some circumstances, an auxiliary return channel from the tower to the television studio, which is coupled to a satellite downlink at the tower facility, may also be provided.
With the advent of and continued industry impetus, as well as expected consumer demand, for high definition television (HDTV), the FCC has begun promulgating rules that will provide an introductory period for the simulcasting (simultaneous broadcasting) of HDTV and NTSC-based programming (which may include separate programs for each format), with an eventual phase-out replacement of the NTSC standard by an HDTV standard (broadcast on UHF channels), exclusively. Discussions between the FCC and the television broadcast industry as to how to accommodate this dual requirement of NTSC and HDTV signalling have included a consideration of allocating additional (currently reserved) bandwidth to the microwave link employed for the transmission of HDTV channels from the television studio to the tower. Because bandwidth conservation is a high FCC priority, and the time and expense of adding additional channel capability equipment for only a limited change-over interval are major concerns of television broadcasting service providers, the allocation of previously reserved bandwidth from the regulated communication spectrum is considered to be a less than ideal way to solve the problem. (The FCC has now made the decision not to allocate additional frequency spectrum for the studio-to-tower microwave link or for tower-to-studio microwave transmissions, even though there are two television signals to be transmitted.)